scholarly journals Evidence of New Particle Formation Within Etna and Stromboli Volcanic Plumes and Its Parameterization From Airborne In Situ Measurements

2019 ◽  
Vol 124 (10) ◽  
pp. 5650-5668 ◽  
Author(s):  
Maher Sahyoun ◽  
Evelyn Freney ◽  
Joel Brito ◽  
Jonathan Duplissy ◽  
Mathieu Gouhier ◽  
...  
Keyword(s):  
Particle Formation ◽  
In Situ Measurements ◽  
New Particle Formation ◽  
Volcanic Plumes

scholarly journals In situ observation of new particle formation (NPF) in the tropical tropopause layer of the 2017 Asian monsoon anticyclone – Part 1: Summary of StratoClim results

2021 ◽  
Vol 21 (15) ◽  
pp. 11689-11722
Author(s):  
Ralf Weigel ◽  
Christoph Mahnke ◽  
Manuel Baumgartner ◽  
Antonis Dragoneas ◽  
Bärbel Vogel ◽  
...  
Keyword(s):  
Asian Monsoon ◽  
Particle Formation ◽  
In Situ Observation ◽  
Aerosol Layer ◽  
New Particle Formation ◽  
Tropical Tropopause Layer ◽  
Temperature Anomalies ◽  
Nucleation Mode ◽  
Tropical Tropopause

Abstract. During the monsoon season of the year 2017 the airborne StratoClim mission took place in Kathmandu, Nepal, with eight mission flights of the M-55 Geophysica in the upper troposphere–lower stratosphere (UTLS) of the Asian monsoon anticyclone (AMA) over northern India, Nepal, and Bangladesh. More than 100 events of new particle formation (NPF) were observed. In total, more than 2 h of flight time was spent under NPF conditions as indicated by the abundant presence of nucleation-mode aerosols, i.e. with particle diameters dp smaller than 15 nm, which were detected in situ by means of condensation nuclei counting techniques. Mixing ratios of nucleation-mode particles (nnm) of up to ∼ 50 000 mg−1 were measured at heights of 15–16 km (θ ≈ 370 K). NPF was most frequently observed at ∼ 12–16 km altitude (θ ≈ 355–380 K) and mainly below the tropopause. Resulting nnm remained elevated (∼ 300–2000 mg−1) up to altitudes of ∼ 17.5 km (θ ≈ 400 K), while under NPF conditions the fraction (f) of sub-micrometre-sized non-volatile residues (dp > 10 nm) remained below 50 %. At ∼ 12–14 km (θ ≈ 355–365 K) the minimum of f (< 15 %) was found, and underneath, the median f generally remains below 25 %. The persistence of particles at nucleation-mode sizes is limited to a few hours, mainly due to coagulation, as demonstrated by a numerical simulation. The frequency of NPF events observed during StratoClim 2017 underlines the importance of the AMA as a source region for UTLS aerosols and for the formation and maintenance of the Asian tropopause aerosol layer (ATAL). The observed abundance of NPF-produced nucleation-mode particles within the AMA is not unambiguously attributable to (a) specific source regions in the boundary layer (according to backward trajectory analyses), or (b) the direct supply with precursor material by convective updraught (from correlations of NPF with carbon monoxide), or (c) the recent release of NPF-capable material from the convective outflow (according to air mass transport times in the tropical tropopause layer, TTL). Temperature anomalies with ΔT of 2 K (peak-to-peak amplitude), as observed at a horizontal wavelength of ∼ 70–100 km during a level flight of several hours, match with NPF detections and represent an additional mechanism for local increases in supersaturation of the NPF precursors. Effective precursor supply and widely distributed temperature anomalies within the AMA can explain the higher frequency of intense NPF observed during StratoClim 2017 than all previous NPF detections with COPAS (COndensation PArticle counting System) at TTL levels over Brazil, northern Australia, or West Africa.

scholarly journals Characterization of satellite based proxies for estimating nucleation mode particles over South Africa

2014 ◽  
Vol 14 (18) ◽  
pp. 25825-25867
Author(s):  
A.-M. Sundström ◽  
A. Nikandrova ◽  
K. Atlaskina ◽  
T. Nieminen ◽  
V. Vakkari ◽  
...  
Keyword(s):  
South Africa ◽  
Industrial Area ◽  
Particle Formation ◽  
Point Sources ◽  
New Particle Formation ◽  
Factors Affecting ◽  
Nucleation Mode ◽  
Sink Term ◽  
Major Factors

Abstract. In this work satellite observations from the NASA's A-Train constellation were used to derive the values of primary emission and regional nucleation proxies over South Africa to estimate the potential for new particle formation. As derived in Kulmala et al. (2011), the satellite based proxies consist of source terms (NO2, SO2 and UV-B radiation), and a sink term describing the pre-existing aerosols. The first goal of this work was to study in detail the use of satellite aerosol optical depth (AOD) as a substitute to the in situ based condensation sink (CS). One of the major factors affecting the agreement of CS and AOD was the elevated aerosol layers that increased the value of column integrated AOD but not affected the in situ CS. However, when the AOD in the proxy sink was replaced by an estimate from linear bivariate fit between AOD and CS, the agreement with the actual nucleation mode number concentration improved somewhat. The second goal of the work was to estimate how well the satellite based proxies can predict the potential for new particle formation. For each proxy the highest potential for new particle formation were observed over the Highveld industrial area, where the emissions were high but the sink due to pre-existing aerosols was relatively low. Best agreement between the satellite and in situ based proxies were obtained for NO2/AOD and UV-B/AOD2, whereas proxies including SO2 in the source term had lower correlation. Even though the OMI SO2 boundary layer product showed reasonable spatial pattern and detected the major sources over the study area, some of the known minor point sources were not detected. When defining the satellite proxies only for days when new particle formation event was observed, it was seen that for all the satellite based proxies the event day medians were higher than the entire measurement period median.

scholarly journals In situ observations of new particle formation in the tropical upper troposphere: the role of clouds and the nucleation mechanism

2011 ◽  
Vol 11 (18) ◽  
pp. 9983-10010 ◽  
Author(s):  
R. Weigel ◽  
S. Borrmann ◽  
J. Kazil ◽  
A. Minikin ◽  
A. Stohl ◽  
...  
Keyword(s):  
South America ◽  
West Africa ◽  
Central America ◽  
Particle Formation ◽  
Tropical Convection ◽  
New Particle Formation ◽  
Upper Troposphere ◽  
Nucleation Mode ◽  
In Situ Observations

Abstract. New particle formation (NPF), which generates nucleation mode aerosol, was observed in the tropical Upper Troposphere (UT) and Tropical Tropopause Layer (TTL) by in situ airborne measurements over South America (January–March 2005), Australia (November–December 2005), West Africa (August 2006) and Central America (2004–2007). Particularly intense NPF was found at the bottom of the TTL. Measurements with a set of condensation particle counters (CPCs) with different dp50 (50% lower size detection efficiency diameter or "cut-off diameter") were conducted on board the M-55 Geophysica in the altitude range of 12.0–20.5 km and on board the DLR Falcon-20 at up to 11.5 km altitude. On board the NASA WB-57F size distributions were measured over Central America in the 4 to 1000 nm diameter range with a system of nucleation mode aerosol spectrometers. Nucleation mode particle concentrations (NNM) were derived from these measurements which allow for identifying many NPF events with NNM in the range of thousands of particles per cm3. Over Australia and West Africa, we identified NPF in the outflow of tropical convection, in particular of a Mesoscale Convective System (MCS). Newly formed particles with NNM > 1000 cm−3 were found to coexist with ice cloud particles (dp > 2 μm) as long as cloud particle concentrations remained below 2 cm−3. The occurrence of NPF within the upper troposphere and the TTL was generally confined within 340 K to 380 K potential temperature, but NPF was of particular strength between 350 K and 370 K (i.e. ~1–4 km below the cold point tropopause). Analyses of the aerosol volatility (at 250 °C) show that in the TTL on average 75–90% of the particles were volatile, compared to typically only 50% in the extra-tropical UT, indicative for the particles to mainly consist of H2SO4-H2O and possibly organic compounds. Along two flight segments over Central and South America (24 February 2005 and 7 August 2006, at 12.5 km altitude) in cloud free air, above thin cirrus, particularly high NNM were observed. Recent lifting had influenced the probed air masses, and NNM reached up to 16 000 particles cm−3 (ambient concentration). A sensitivity study using an aerosol model, which includes neutral and ion induced nucleation processes, simulates NNM in reasonable agreement with the in situ observations of clear-air NPF. Based on new, stringent multi-CPC criteria, our measurements corroborate the hypothesis that the tropical UT and the TTL are regions supplying freshly nucleated particles. Our findings narrow the altitude of the main source region to the bottom TTL, i.e. to the level of main tropical convection outflow, and, by means of measurements of carbon monoxide, they indicate the importance of anthropogenic emissions in NPF. After growth and/or coalescence the nucleation mode particles may act as cloud condensation nuclei in the tropical UT, or, upon ascent into the stratosphere, contribute to maintain the stratospheric background aerosol.

scholarly journals New particle formation inside ice clouds: In-situ observations in the tropical tropopause layer of the 2017 Asian Monsoon Anticyclone

2021 ◽  
Author(s):  
Ralf Weigel ◽  
Christoph Mahnke ◽  
Manuel Baumgartner ◽  
Martina Krämer ◽  
Peter Spichtinger ◽  
...  
Keyword(s):  
Ultrafine Particles ◽  
Asian Monsoon ◽  
Particle Formation ◽  
New Particle Formation ◽  
Mixing Ratios ◽  
Microphysical Properties ◽  
Tropical Tropopause ◽  
Ice Particles ◽  
Cloud Ice

Abstract. From 27 July to 10 August 2017 the airborne StratoClim mission took place in Kathmandu, Nepal where eight mission flights were conducted with the M-55 Geophysica up to altitudes of 20 km. New Particle Formation (NPF) was identified by the abundant presence of ultrafine aerosols, with particle diameters dp smaller than 15 nm, which were in-situ detected by means of condensation nuclei counting techniques. NPF fields in clear-skies as well as in the presence of cloud ice particles (dp > 3 µm) were encountered at upper troposphere/lowermost stratosphere (UT/LS) levels and within the Asian Monsoon Anticyclone (AMA). NPF-generated ultrafine particles in elevated concentrations (Nuf) were frequently found together with cloud ice (in number concentrations Nice of up to 3 cm−3) at heights between ~ 11 km and 16 km. From a total measurement time of ~ 22.5 hours above 10 km altitude, in-cloud NPF was in sum detected over ~ 1.3 hours (~ 50 % of all NPF records throughout StratoClim). Maximum Nuf of up to ~ 11000 cm−3 were detected coincidently with intermediate ice particle concentrations Nice of 0.05–0.1 cm−3 at comparatively moderate carbon monoxide (CO) contents of ~ 90–100 nmol mol−1. Neither under clear-sky nor during in-cloud NPF do the highest Nuf concentrations correlate with the highest CO mixing ratios, suggesting that an elevated pollutant load is not a prerequisite for NPF. Under clear-air conditions, NPF with elevated Nuf (> 8000 cm−3) occurred slightly less often than within clouds. In the presence of cloud ice, NPF with Nuf between 1500–4000 cm−3 were observed about twice as often as under clear air conditions. When ice water contents exceeded 1000 µmol mol−1 in very cold air ( 5000 mg−1) were rarely observed (~ 6 % of in-cloud NPF data). For specifying the constraining mechanisms for NPF possibly imposed by the microphysical properties of the cloud elements, the integral radius (IR) of the ice cloud population was identified as the most practicable indicator. Neither of both, the number of ice particles or the free distance between the ice particles, is clearly related to the NPF-rate detected. The results of a numerical simulation indicates how the IR affects the supersaturation of a condensable vapour, such as sulphuric acid, and that IR determines the effective limitation of NPF rates due to cloud ice.

scholarly journals Ice particle formation and sedimentation in the tropopause region: A case study based on in situ measurements of total water during POLSTAR 1997

1999 ◽  
Vol 26 (14) ◽  
pp. 2219-2222 ◽  
Author(s):  
C. Schiller ◽  
A. Afchine ◽  
N. Eicke ◽  
C. Feigl ◽  
H. Fischer ◽  
...  
Keyword(s):  
Particle Formation ◽  
In Situ Measurements ◽  
Total Water ◽  
Tropopause Region

scholarly journals In situ observations of new particle formation in the tropical upper troposphere: the role of clouds and the nucleation mechanism

2011 ◽  
Vol 11 (3) ◽  
pp. 9249-9312 ◽  
Author(s):  
R. Weigel ◽  
S. Borrmann ◽  
J. Kazil ◽  
A. Minikin ◽  
A. Stohl ◽  
...  
Keyword(s):  
South America ◽  
West Africa ◽  
Ultrafine Particles ◽  
Particle Formation ◽  
New Particle Formation ◽  
Upper Troposphere ◽  
Research Aircraft ◽  
In Situ Observations ◽  
Tropical Upper Troposphere

Abstract. New particle formation which generates ultrafine aerosol was observed in the continental tropical Upper Troposphere (UT) and Tropical Tropopause Layer (TTL), particularly at the bottom of the TTL, by in situ airborne measurements over South America (January–March, 2005) and West Africa (August, 2006). Measurements with a set of condensation particle counters with different dp50 (50% detection efficiency cut-off particle diameter) were conducted in the altitude range of 12.0–20.5 km on board the high altitude research aircraft M-55 "Geophysica" and at up to 11.5 km altitude on board the research aircraft DLR Falcon-20. Concentrations of ultrafine particles in the size range of 6 to 15 nm were derived from these measurements and several events of new particle formation (NPF) were identified. For two flight segments (24 February 2005 and 7 August 2006, at 12.5 km altitude) when recent lifting had influenced the probed air mass, the concentration of ultrafine particles reached up to 16 000 particles cm−3 (ambient concentration). A sensitivity study by using an aerosol model which includes neutral and ion induced nucleation processes revealed predicted concentrations of ultrafine particles in reasonable agreement with the in situ observations. NPF over South America was observed in cloud free air, above thin cirrus, while over West Africa, in the outflow of a Mesoscale Convective System (MCS), newly formed particles in the range of several hundred per cm3 were found to coexist with ice cloud particles as long as the concentration of cloud particles (dp>2 μm) remained below 2 cm−3. The occurrence of NPF within the upper troposphere and the TTL was generally confined within an altitude band extending from 340 K to 380 K potential temperature, of particular strength between 350 K and 370 K. By means of a heated aerosol inlet line (at 250 °C) measurements of particle volatility were performed which show that within the TTL over South America and West Africa, on average 10–25% of the particles contained non-volatile cores. In background UT/TTL conditions the fractions of non-volatile particles typically ranged up to 50%. Our measurements provide further evidence for the hypothesis that the tropical UT and the TTL are aerosol source regions supplying freshly nucleated particles which, if lifted, may contribute to maintain the stratospheric background aerosol. These particles can become important for cloud formation in the tropical upper troposphere, if they further grow such that they can act as cloud condensation nuclei.

Modelling new particle formation in a passive volcanic plume using a new parameterisation in WRF-Chem - effects on climate-relevant variables at the regional scale

2020 ◽  
Author(s):  
Céline Planche ◽  
Clémence Rose ◽  
Sandra Banson ◽  
Aurelia Lupascu ◽  
Mathieu Gouhier ◽  
...  
Keyword(s):  
Volcanic Eruption ◽  
Cluster Formation ◽  
Formation Rate ◽  
Regional Scale ◽  
Particle Formation ◽  
Volcanic Plume ◽  
New Particle Formation ◽  
Piton De La Fournaise ◽  
Volcanic Plumes ◽  
Eruption Plume

&lt;p&gt;New particle formation (NPF) is an important source of aerosol particles at&amp;#160; global scale, including, in particular, cloud condensation nuclei (CCN). NPF has been observed worldwide in a broad variety of environments, but some speci&amp;#64257;c conditions, such as those encountered in volcanic plumes, remain poorly documented in the literature. Yet, these conditions could promote the occurrence of the process, as recently evidenced in the volcanic eruption plume of the Piton de la Fournaise (Rose at al. 2019); a dominant fraction of the volcanic particles was moreover found to be of secondary origin in the plume, further highlighting the importance of the particle formation and growth processes associated to the volcanic plume eruption. A deeper comprehension of such natural processes is thus essential to assess their climate-related effects at present days but also to better de&amp;#64257;ne pre-industrial conditions and their variability in climate model simulations.&lt;/p&gt;&lt;p&gt;Sulfuric acid (SA) is commonly accepted as one of the main precursors for atmospheric NPF, and its role could be even more important in volcanic plume conditions, as recently evidenced by the airborne measurements conducted in the passive volcanic plumes of Etna and Stromboli (Sahyoun et al., 2019). Indeed, the flights performed in the frame of the STRAP campaign have allowed direct measurement of SA in such conditions for the first time, and have highlighted a strong connection between the cluster formation rate and SA concentration. Following these observations, the objective of the present work was to further quantify the formation of new particles in a volcanic plume and assess the effects of the process at a regional scale. For that purpose, the new parameterisation of nucleation derived by Sahyoun et al. (2019) was introduced in the model WRF-Chem, further optimized for the description of NPF. The flight ETNA13 described in detail in Sahyoun et al. (2019) was used as a case study to evaluate the effect of the new parameterisation on the cluster formation rate and particle number concentration in various size ranges, including CCN (i.e. climate-relevant) sizes.&lt;/p&gt;&lt;p&gt;&lt;strong&gt;References: &lt;/strong&gt;&lt;/p&gt;&lt;p&gt;Sahyoun, M., Freney, E., Brito, J., Duplissy, J., Gouhier, M., Colomb, A., Dupuy, R., Bourianne, T., Nowak, J. B., Yan, C., Pet&amp;#228;j&amp;#228;, T., Kulmala, M., Schwarzenboeck, A., Planche, C., and Sellegri, K.: Evidence of new particle formation within Etna and Stromboli volcanic plumes and its parameterization from airborne in-situ measurements, J. Geophys. Res.-Atmos., 124, 5650&amp;#8211;5668, https://doi.org/10.1029/2018JD028882, 2019.&lt;/p&gt;&lt;p&gt;Rose, C., Foucart, B., Picard, D., Colomb, A., Metzger, J.-M., Tulet, P., and Sellegri, K.: New particle formation in the volcanic eruption plume of the Piton de la Fournaise: specific features from a long-term dataset, Atmos. Chem. Phys., 19, 13243&amp;#8211;13265, https://doi.org/10.5194/acp-19-13243-2019, 2019.&lt;/p&gt;

scholarly journals In situ measurements of tropospheric volcanic plumes in Ecuador and Colombia during TC4

2011 ◽  
Vol 116 ◽  
Author(s):  
S. A. Carn ◽  
K. D. Froyd ◽  
B. E. Anderson ◽  
P. Wennberg ◽  
J. Crounse ◽  
...  
Keyword(s):  
In Situ Measurements ◽  
Volcanic Plumes
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